Reacting Flow Nomenclature


$a$	Under-relaxation factor, specified as a value in a Reacting Channel Co-Simulation Zone [dimensionless]
$a_{i}$	Activity of species $i$ [dimensionless]
$A$	Helmholtz free energy [J].
$A_{e}$	Atomic weight of element $e$ [kg/kmol]
$A_{j}$	Pre-exponential factor [(kmol/m³)^(1-p_j)/s] The units for the pre-exponent $A_{j}$ change according to the order of the reaction $p_{j}$ and the temperature dependency $β$ For example, for a bi-molecular reaction where $β = 0$ , $A_{j}$ is of unit m³/kmol/s.
$A_{p}$	Surface area of the particle [m²]
$A_{p l}$	Arrhenius pre-exponential factor for char oxidation reaction $l$ [m/s/K^$n$] where $n$ is the temperature exponent
$A_{p n}$	Arrhenius pre-exponential factor for devolatilization reaction $n$ [1/s]
$α$	Coefficient imported in TROE mechanism / Mass fraction of coal component
$α_{i}$	Mass fraction of $i$ th component in particle [dimensionless]
$α_{j i}$	Collision efficiency of the third body in a reaction
$b$	Regress variable
$β$	Temperature exponent / an Arrhenius parameter
$c$	Normalized progress variable
$C_{g}$	Overall gas concentration [kmol/m³]
$C_{o l g}$	Concentration of oxidizer [kmol/m³]
$C_{p}$	Heat capacity at constant pressure [J/kg/K]
$C_{V}$	Heat capacity at constant volume [J/kg/K]
$c f$	Correction factor, used to change the pre-exponential factor in the NOx prompt rate constant equation, or for fuel NOx.
$χ$	Porosity
$d$	Particle diameter [m] / Soot Mean Diameter [m]
$D_{C}$	Channel diameter [m], calculated from the inlet area that you specify as a value in a reacting channel zone.
$D_{m}$	Diffusion coefficient [m²/s]
$D_{p}$	Equivalent Packed Bed Particle Diameter [m], which you can specify as a value in a reacting channel zone.
$E_{a}$	Activation energy [J/kmol]
$f$	Initiator frequency / Pipe Friction Factor, which you can specify as a condition for each zone (for reacting channels)
$f_{h t g}$	Heat Transfer Factor, which you can specify as a value for a zone within a packed bed reacting channel.
$f_{i}$	Initiator efficiency
$f (i, s o o t)$	Size repartition of section $i$ [1/m³]
$f_{v}$	Soot volume fraction [dimensionless]
$F$	Factor used to calculate the rate constant for the production of NOx prompt
$F$	Blending function / thickening factor
$G$	Gibbs free energy [J]
$γ$	Heat loss ratio [dimensionless]
$Γ_{t o t}$	Total surface site concentration [mol/m²]
$Γ_{y}$	Combustion scalar diffusion coefficient for the unnormalized progress variable.
$h_{f}$	Convective heat transfer coefficient of the reacting channel, specified as a condition in a Reacting Channel Co-Simulation Zone.
$H$	Enthalpy [J/kg]
$I$	Initiator
$Ø_{N}$	Soot scaled number density
$Ø_{M}$	Soot scaled mass density
$k$	Reaction rate coefficient (units vary: Char Oxidation [m/s] and Devolatilization [1/s])
$k_{c p l}$	Mass transfer coefficient
$k_{m}$	Mass transfer coefficient [m/s]
$K$	Equilibrium constant
$K_{a}$	Planck Mean Absorption Coefficient
$K_{C}$	Gas phase thermal conductivity, [W/m/K]
$K_{f}$	User-defined reaction coefficient [(kmol/m³)^(1-N_j)/s]
$λ_{i}$	Live polymer with $i$ th moment
$m$	Total mass in a CFD cell
$\dot{m}$	Mass flux in a CFD cell
$m_{i}$	Mass of $i$ th component in a particle / Total mass of species $i$ in a mixture
$m_{p}$	Particle mass
$M$	Soot mass density
$M_{w}$	Molecular Weight [kg/mol]
${M_{w}}_{i}$	Molecular Weight of species $i$ / Molecular Weight of an ion [kg/mol]
${\bar{M}}_{w}$	Mean Molecular Weight of a mixture [kg/mol]
$M_{r}$	$r$ th Moment
$μ$	Gas viscosity, which you can specify with the Reacting Channel Inlet Viscosity Option for a zone.
$μ_{i}$	Dead polymer with $i$ th moment / chemical potential of species $i$
$μ_{t}$	Turbulent viscosity
$n_{i}$	Number of moles of species $i$ in a mixture
N	Soot number density
$N_{A}$	Avogadro constant $6.02214179 \times 10^{26}$ [1/kmol]
$N_{j}$	Sum of all $ν_{i}$ for reaction $j$ [dimensionless]
$N u$	Nusselt number, determined according to fully developed pipe flow empirical calculations [dimensionless]
$ζ_{p l}$	Particle pore area coefficient
$P$	Pressure [Pa] / dead polymer
$\Pr$	Prandtl number [dimensionless]
$P (z, b; \underset{̲}{x}, t)$	Joint pdf of the mixture fraction $z$ and regress variable $b$
$P_{b} (b; \underset{̲}{x}, t)$	A marginal pdf
$P_{j}$	Sum of all $p_{i j}$ for reaction $j$ [dimensionless]
$P_{n}$	Dead polymer with $n$ monomer units
$P_{r}$	Reduced pressure in pressure dependant reactions
$P_{z} (z \| b; \underset{̲}{x}, t)$	A conditional pdf on $b$
$ϕ$	Ratio of stoichiometric coefficients of solid and gas reactants [dimenionless] / Thiele modulus [dimensionless]
$Φ$	Equivalence ratio
$Ψ$	Stoichiometric mass ratio
$q_{i} (v)$	Soot volume distribution within section $i$ [1/m³]
$\tilde{Q}$	Favre average of quantity $Q$
${\tilde{Q}}^{u} (\underset{̲}{x}, t)$	Favre averaged quantity at unburnt state
${\tilde{Q}}^{b} (\underset{̲}{x}, t)$	Favre averaged quantity at burned state
${\dot{Q}}_{C}$	Convective heat transfer source, [W/m²]
${\dot{Q}}_{C}^{0}$	Heat flux from previous iteration [W/m²]
$Q_{i}$	Total volume fraction
${\dot{Q}}_{3 D}$	Heat flux boundary condition at the reacting channel wall [W/m²]
$r$	Reaction rate [kg/s]
$\hat{r_{i}}$	Net molar rate of change (production or consumption) of species $i$ [kg/s]
$r_{k}$	Reaction rate / rate of consumption of solid reactant [kg/s]
$r_{v p n}$	Production rate of volatiles for particle p and nth devolatilization step [kg/s]
$r_{h p l}$	Overall combined char reaction rate [kg/s]
$r_{h p n}$	Production rate of char for particle p and nth devolatilization step [kg/s]
$r_{p}$	Total reaction rate of coal particle p [kg/s]
$r_{w p}$	Moisture evaporation rate [kg/s]
$R$	Live Polymer
$R^{.}$	Radical
$R$	Reaction [dimensionless]
$R_{j}$	Final reaction rate [kmol/s/m³]
$R_{n}$	Live polymer with $n$ monomer units
$R_{u}$	Universal gas constant $8314.4621$ [J/kmol/K]
$ρ$	Density [kg/m³]
$ρ_{s o o t}$	Soot Density (default value = 1800kg/m³ )
$(ρ Y_{i}) / M_{i}$	Molar concentration [kmol/m³]
$σ_{t}$	Turbulent Schmidt Number
$s_{c}$	Sticking coefficient for surface reactions
$S$	Solvent (polymerization) / Soot Surface Density [m²/m³] / Entropy [J/K]
$S_{E}$	Source term
$S_{i}$	Chemical source term
$S h$	Sherwood number [dimensionless]
$t$	Physical time [s]
$T$	Temperature [K]
$T^{β_{j}}$	Temperature to the exponent $β_{j}$ [dimensionless]
$T_{p}$	Particle temperature [K]
$T$	Reacting channel bulk temperature, [K], specified as a value in a Reacting Channel Co-Simulation Zone.
$T_{W}$	Reacting channel wall temperature, [K], which is averaged from the 3D outer flow temperature field on the resolved reacting channel wall.
$τ$	Time scale [s]
$τ_{m i x}$	Turbulent mixing time scale [s]
$τ_{k i n}$	Time scale that is derived from chemical reaction rate from finite-rate kinetics [s]
$τ_{r e s}$	Residence time in the cell [s]
$τ_{t u r b}$	Turbulent time scale [s]
$U$	Total internal energy [J]
$ν_{P A H}$	polyaromatic hydrocarbon (PAH) volume [m³]
$ν_{C 2}$	C2 volume [m³]
$V$	Volume [m³]
$υ_{i j}$	Stoichiometric coefficient of reacting species $i$ in reaction $j$ [dimensionless]
$φ_{l}$	Stoichiometric coefficient for the char reaction [dimensionless]
$W_{i}$	Weight of species $i$ [kg]
$\underset{̲}{x}$	Position vector [m]
$X_{i}$	Mole fraction of species $i$ [dimensionless]
$y$	(Unnormalized) progress variable
$y_{var}$	(Unnormalized) progress variable variance
$Y$	Mass fraction vector
$Y Y_{p n}$	Mass stoichiometric coefficient for particle devolatilization reaction, n
$Y_{i}$	Mass fraction of species $i$ [dimensionless]
$Ω_{i}$	Source term of species $i$ [kg/s/m³]
$ω_{i}$	Species source term
$ω_{k}$	Reaction source term
$Z$	Mixture fraction [dimensionless]
$Z_{var}$	Mixture fraction variance [dimensionless]

Particle Chemistry Subscripts


w	moisture component
c	raw coal component
h	char component
v	volatile matter
n	devolatilization step
l	char oxidation reaction
g	gas phase
p	particle phase